JP2013178408A - Liquid crystal optical element and three-dimensional image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal optical element having excellent optical characteristics and a three-dimensional image display device with the liquid crystal optical element.SOLUTION: According to an embodiment, the liquid crystal optical element comprises a first substrate part, a second substrate part and a liquid crystal layer. The first substrate part includes a first substrate and a plurality of first electrodes. The first substrate has a first main surface. The plurality of first electrodes are provided on the first main surface, extend in a first direction and are arranged in a second direction orthogonal to the first direction. The second substrate part includes a second substrate and a second electrode. The second substrate has a second main surface facing the first main surface. The second electrode is provided on the second main surface and faces the plurality of first electrodes, respectively. The liquid crystal layer is provided between the first substrate part and the second substrate part. The plurality of first electrodes each have a concave part on a counter surface facing the second electrode.

Description

  Embodiments described herein relate generally to a liquid crystal optical element and a stereoscopic image display apparatus.

  A liquid crystal optical element is known that utilizes the birefringence of liquid crystal molecules and changes the refractive index distribution in response to application of a voltage. There is also a stereoscopic image display device in which the liquid crystal optical element and an image display unit are combined.

  In the stereoscopic image display device, by changing the refractive index distribution of the liquid crystal optical element, a state in which the image displayed on the image display unit is directly incident on the observer's eyes and a plurality of images displayed on the image display unit are displayed. The parallax image is switched to a state of being incident on the observer's eyes. Thereby, a high-definition two-dimensional pixel display operation and a stereoscopic three-dimensional image display operation with the naked eye using a plurality of parallax images are realized. In a liquid crystal optical element used for a stereoscopic image display device, it is desired to realize good optical characteristics.

JP 2010-224191 A

  Embodiments of the present invention provide a liquid crystal optical element having good optical characteristics and a stereoscopic image display device including the liquid crystal optical element.

  According to an embodiment of the present invention, a liquid crystal optical element including a first substrate unit, a second substrate unit, and a liquid crystal layer is provided. The first substrate unit includes a first substrate and a plurality of first electrodes. The first substrate has a first main surface. The plurality of first electrodes are provided on the first main surface, extend along the first direction, and are arranged in a second direction perpendicular to the first direction. The second substrate unit includes a second substrate and a second electrode. The second substrate has a second main surface facing the first main surface. The second electrode is provided on the second main surface and faces each of the plurality of first electrodes. The liquid crystal layer is provided between the first substrate unit and the second substrate unit. The plurality of first electrodes have a recess on an opposing surface facing the second electrode.

FIG. 1A and FIG. 1B are schematic cross-sectional views illustrating the configuration of a stereoscopic image display device according to the first embodiment. 1 is a schematic perspective view illustrating the configuration of a part of a stereoscopic image display device according to a first embodiment. FIG. 3A and FIG. 3B are schematic cross-sectional views illustrating the configuration of part of the stereoscopic image display device according to the first embodiment. FIG. 4A to FIG. 4E are schematic perspective views illustrating the configuration of a part of another stereoscopic image display device according to the first embodiment. FIG. 6 is a schematic cross-sectional view illustrating the configuration of a stereoscopic image display device according to a second embodiment. FIG. 6 is a schematic cross-sectional view illustrating the configuration of a part of another stereoscopic image display device according to a second embodiment. FIG. 10 is a schematic cross-sectional view illustrating the configuration of a stereoscopic image display device according to a third embodiment. FIG. 10 is a schematic perspective view illustrating the configuration of a part of a stereoscopic image display device according to a third embodiment. FIG. 9A to FIG. 9E are schematic perspective views illustrating the configuration of part of another stereoscopic image display device according to the third embodiment. FIG. 9 is a schematic cross-sectional view illustrating the configuration of another stereoscopic image display device according to a third embodiment. FIG. 10 is a schematic cross-sectional view illustrating the configuration of a part of another stereoscopic image display device according to a third embodiment.

Each embodiment will be described below with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1A and FIG. 1B are schematic cross-sectional views illustrating the configuration of a stereoscopic image display device according to the first embodiment.
FIG. 2 is a schematic perspective view illustrating the configuration of a part of the stereoscopic image display apparatus according to the first embodiment.
FIG. 1A and FIG. 1B schematically show a cross section taken along line A1-A2 of FIG. FIG. 1B is an enlarged view of a part of FIG.

As illustrated in FIG. 1A and FIG. 2, the stereoscopic image display device 210 includes a liquid crystal optical element 110, an image display unit 120, and a drive unit 130.
The image display unit 120 has an image display surface 120a for displaying an image. The image display surface 120a has a rectangular shape, for example.
The liquid crystal optical element 110 is provided on the image display surface 120a. The liquid crystal optical element 110 covers, for example, the image display surface 120a. The liquid crystal optical element 110 functions as, for example, a liquid crystal GRIN lens (Gradient Index lens). The refractive index distribution of the liquid crystal optical element 110 can be changed. One state of the refractive index distribution corresponds to a first state in which the image displayed on the image display surface 120a is directly incident on the observer's eyes. Another state of the refractive index distribution corresponds to a second state in which the image displayed on the image display unit 120 is incident on the observer's eyes as a plurality of parallax images.

  In the stereoscopic image display device 210, by changing the refractive index distribution of the liquid crystal optical element 110, a two-dimensional image display (hereinafter referred to as 2D display) and a three-dimensional view that can be stereoscopically viewed with the naked eye. Image display (hereinafter referred to as 3D display) can be selectively switched.

  The drive unit 130 is electrically connected to the liquid crystal optical element 110. In this example, the drive unit 130 is further electrically connected to the image display unit 120. The drive unit 130 controls operations of the liquid crystal optical element 110 and the image display unit 120. For example, the driving unit 130 switches between the first state and the second state of the liquid crystal optical element 110. A video signal is input to the drive unit 130 by a recording medium, an external input, or the like. The drive unit 130 controls the operation of the image display unit 120 based on the input video signal. As a result, an image corresponding to the input video signal is displayed on the image display surface 120a. The drive unit 130 may be included in the image display unit 120.

  When performing the 2D display, the driving unit 130 sets the liquid crystal optical element 110 to the first state and causes the image display unit 120 to display an image for 2D display. On the other hand, when performing the 3D display, the driving unit 130 sets the liquid crystal optical element 110 to the second state and causes the image display unit 120 to display an image for 3D display.

  The liquid crystal optical element 110 includes a first substrate unit 11 s, a second substrate unit 12 s, and a liquid crystal layer 30. The first substrate unit 11 s includes the first substrate 11 and the first electrode 21. The second substrate unit 12 s includes the second substrate 12 and the second electrode 22.

  The first substrate 11 has a first main surface 11a. The second substrate 12 has a second main surface 12a facing the first main surface 11a. A plurality of first electrodes 21 are provided on the first major surface 11a. The plurality of first electrodes 21 each extend along the first direction and are arranged at intervals in a second direction perpendicular to the first direction. The interval between the plurality of first electrodes 21 is, for example, constant.

  A direction perpendicular to the first main surface 11a and the second main surface 12a is taken as a Z-axis direction. One direction perpendicular to the Z-axis direction is taken as an X-axis direction. A direction perpendicular to each of the Z-axis direction and the X-axis direction is taken as a Y-axis direction. In this example, the Y-axis direction is the first direction. The X-axis direction is the second direction. However, in the embodiment, it may be an arbitrary direction perpendicular to the Z-axis direction, and the first direction may be an arbitrary direction along the first main surface 11a.

  The shape of the first electrode 21 is, for example, a substantially rectangular shape when viewed in the Z-axis direction. The length of the first electrode 21 in the Y-axis direction is slightly longer than the length of the image display surface 120a in the Y-axis direction. The first electrode 21 crosses the image display surface 120a in the Y-axis direction.

  The first major surface 11a is substantially parallel to the second major surface 12a. In this example, one of the two mutually perpendicular sides of the rectangular image display surface 120a is parallel to the X-axis direction, and the other side is parallel to the Y-axis direction. The direction of the side of the image display surface 120a is not limited to this, and may be any direction perpendicular to the Z-axis direction.

  One ends of the plurality of first electrodes 21 are connected to the wiring portion 41. The shape including the plurality of first electrodes 21 and the wiring portion 41 is a comb blade shape. By applying a voltage to the wiring part 41, it is possible to apply a voltage to each of the plurality of first electrodes 21.

  The second substrate unit 12s faces the first substrate unit 11s. The second main surface 12a of the second substrate 12 faces the first main surface 11a. The second electrode 22 is provided on the second major surface 12a. The second electrode 22 faces each of the plurality of first electrodes 21. The second electrode 22 is larger than the first electrode 21 and covers the first electrode 21 when viewed in the Z-axis direction.

  The plurality of first electrodes 21 and the second electrodes 22 are electrically connected to the driving unit 130 by wirings not shown. Application of voltage (setting of potential) to the plurality of first electrodes 21 and second electrodes 22 is controlled by the drive unit 130. Switching between the first state and the second state of the liquid crystal optical element 110 is performed by applying a voltage to the plurality of first electrodes 21 and second electrodes 22.

  The liquid crystal layer 30 is provided between the first substrate unit 11s and the second substrate unit 12s. The liquid crystal layer 30 includes a liquid crystal material 36 including a plurality of liquid crystal molecules 35. The liquid crystal material 36 is a liquid crystalline medium. For the liquid crystal layer 30, for example, nematic liquid crystal is used. The dielectric anisotropy of the liquid crystal layer 30 is positive or negative. Hereinafter, a case where a nematic liquid crystal having positive dielectric anisotropy is used as the liquid crystal layer 30 will be described.

  A first alignment film 31 is provided between the first substrate unit 11 s and the liquid crystal layer 30. The first alignment film 31 horizontally aligns the liquid crystal molecules 35. A second alignment film 32 is provided between the second substrate unit 12 s and the liquid crystal layer 30. The second alignment film 32 horizontally aligns the liquid crystal molecules 35. The first alignment film 31 and the second alignment film 32 direct the director (long axis) of the liquid crystal molecules 35 in the X-axis direction. Thereby, the liquid crystal material 36 exhibits horizontal alignment in a state where no voltage is applied to the plurality of first electrodes 21 and the second electrodes 22 (state shown in FIG. 1).

  Here, the horizontal alignment includes, for example, a state in which the major axis of the liquid crystal molecules 35 is in the range of 0 ° to 30 ° when the direction perpendicular to the Z-axis direction is 0 °. That is, the pretilt angle in the horizontal alignment is, for example, 0 ° or more and 30 ° or less. The liquid crystal layer 30 may be vertically aligned or hybrid aligned (HAN alignment).

  Transparent materials are used for the first substrate 11, the second substrate 12, the first electrode 21, and the second electrode 22. The light including the image displayed on the image display unit 120 passes through them.

For the first substrate 11 and the second substrate 12, for example, glass or resin is used. The first electrode 21 and the second electrode 22 include, for example, an oxide containing at least one element selected from the group consisting of In, Sn, Zn, and Ti. For example, ITO is used for the first electrode 21 and the second electrode 22. For example, the first electrode 21 and the second electrode 22 may be at least one of In ₂ O ₃ and SnO ₃ . The first electrode 21 and the second electrode 22 may be a thin metal layer, for example.

  For the first alignment film 31 and the second alignment film 32, for example, a resin such as polyimide is used. The film thickness of the first alignment film 31 and the second alignment film 32 is, for example, 200 nm (for example, not less than 100 nm and not more than 300 nm). For the wiring part 41, for example, a material used for the first electrode 21 and the second electrode 22 is used.

  As shown in FIG. 1B, each of the plurality of first electrodes 21 has a recess 40 on the facing surface 21 a that faces the second electrode 22. The first substrate unit 11 s includes an insulating layer 42 provided between the first substrate 11 and each of the plurality of first electrodes 21. The insulating layer 42 is light transmissive. For the insulating layer 42, for example, an inorganic material such as silicon oxide and an organic material such as acrylic resin or polyimide resin are used. The material used for the insulating layer 42 may have photosensitivity.

  The insulating layer 42 has a hole 42 a in a portion facing the first electrode 21. The hole 42a penetrates the insulating layer 42 along the Z-axis direction. Alternatively, the depth of the hole 42 a is shallower than the thickness of the insulating layer 42. The recess 40 is along the hole 42a. The recess 40 is formed, for example, by allowing a part of the first electrode 21 to enter the hole 42a. Thus, the recessed part 40 is a part which entered the hole 42a of the 1st electrode 21, for example. The shape of the hole 42a viewed in the Z-axis direction is, for example, a rectangular shape. Accordingly, the shape of the recess 40 viewed in the Z-axis direction is, for example, a rectangular shape.

  The plurality of first electrodes 21 each have a plurality of recesses 40 arranged along the Y-axis direction. For example, the plurality of recesses 40 are arranged substantially in a straight line along the Y-axis direction. Moreover, each of the plurality of recesses 40 is periodically arranged, for example. Each of the plurality of recesses 40 is arranged at substantially equal intervals, for example.

  A distance D1 between two adjacent recesses 40 is equal to or less than the width W1 of the first electrode 21 in the X-axis direction. In the two recesses 40 adjacent to each other, the width W2 of the recess 40 is larger than the distance D1 between the recess 40 and the adjacent recess 40. Further, the depth D2 from the facing surface 21a of the recess 40 is smaller than the width W1 of the first electrode 21 in the X-axis direction. A width W1 of the first electrode 21 in the X-axis direction is, for example, not less than 10 μm and not more than 100 μm. The depth D2 from the facing surface 21a of the recess 40 is, for example, 1 μm (for example, 0.5 μm or more and 2 μm or less).

  The image display unit 120 includes a plurality of pixel groups 50 arranged in a two-dimensional matrix. The image display surface 120a is formed by the plurality of pixel groups 50. The pixel group 50 includes, for example, a first pixel PX1, a second pixel PX2, and a third pixel PX3. Hereinafter, when the first pixel PX1 to the third pixel PX3 are combined, they are referred to as a pixel PX. The pixel group 50 is disposed to face the area AR1 between the two adjacent first electrodes 21. The first pixel PX1 to the third pixel PX3 included in the pixel group 50 are arranged in the X-axis direction. The plurality of pixels PX included in the pixel group 50 is not limited to three, and may be two or four or more.

  The image display unit 120 emits light including an image to be displayed on the image display surface 120a, for example. This light is in a linearly polarized state that travels substantially in the Z-axis direction. The polarization axis of this linearly polarized light (azimuth axis in the XY plane of the vibration plane of the electric field) is the X-axis direction. That is, the polarization axis of this linearly polarized light is a direction parallel to the director (long axis) of the liquid crystal molecules 35. This linearly polarized light is formed, for example, by arranging an optical filter (polarizer) having a polarization axis in the X-axis direction on the optical path.

  As shown in FIG. 1A, each of the plurality of liquid crystal molecules 35 included in the liquid crystal layer 30 has a horizontal alignment when no voltage is applied to the plurality of first electrodes 21 and the second electrodes 22. Become. Thereby, a substantially uniform refractive index distribution is shown in the X-axis direction and the Y-axis direction. For this reason, when no voltage is applied, the traveling direction of the light including the image displayed on the image display unit 120 is not substantially changed. The liquid crystal optical element 110 is in the first state when no voltage is applied.

  When switching the liquid crystal optical element 110 from the first state to the second state, for example, a voltage is applied between the plurality of first electrodes 21 and the second electrodes 22.

FIG. 3A and FIG. 3B are schematic cross-sectional views illustrating the configuration of part of the stereoscopic image display device according to the first embodiment.
As shown in FIG. 3A, when a voltage is applied to each of the plurality of first electrodes 21 and second electrodes 22, electric lines of force EL from the first electrode 21 toward the second electrode 22 are generated. The electric lines of force EL have, for example, a symmetrical distribution with the first electrode 21 as the center.

  FIG. 3B schematically illustrates the orientation of the liquid crystal molecules 35 in the liquid crystal layer 30. As shown in FIG. 3B, when the dielectric anisotropy of the liquid crystal layer 30 is positive, the orientation of the liquid crystal molecules 35 in the dense region (that is, the strong electric field region) of the electric force lines EL is the electric force lines EL. Deforms along the path. In the first portion 30a of the liquid crystal layer 30 where the first electrode 21 and the second electrode 22 face each other, the tilt angle of the liquid crystal molecules 35 is increased. On the other hand, in the second portion 30 b near the center of the two adjacent first electrodes 21 in the liquid crystal layer 30, the liquid crystal molecules 35 remain in horizontal alignment. Then, in the portion between the first portion 30a and the second portion 30b, the angle (tilt angle) of the liquid crystal molecules 35 changes so as to gradually approach vertical alignment from the second portion 30b toward the first portion 30a. To do. The liquid crystal molecules 35 change the major axis angle of the liquid crystal molecules 35 in the ZX plane along the electric field lines EL. The angle of the major axis of the liquid crystal molecules 35 changes with the Y axis as the rotation axis.

  The liquid crystal molecules 35 have birefringence. The refractive index for the polarized light in the major axis direction of the liquid crystal molecules 35 is higher than the refractive index in the minor axis direction of the liquid crystal molecules 35. When the angle of the liquid crystal molecules 35 is changed as described above, the refractive index of the liquid crystal layer 30 relating to linearly polarized light traveling in the Z-axis direction and having the polarization axis in the X-axis direction is the second portion 30b of the liquid crystal layer 30. And gradually decreases toward the first portion 30a. Thereby, a convex lens-like refractive index distribution is formed.

  The multiple first electrodes 21 extend along the Y-axis direction. For this reason, the refractive index distribution of the liquid crystal layer 30 at the time of voltage application is a cylindrical lens shape extending along the Y-axis direction. The plurality of first electrodes 21 are arranged along the X-axis direction. Therefore, the refractive index distribution of the liquid crystal layer 30 when a voltage is applied is a lenticular lens shape in which a plurality of cylindrical lenses extending in the Y-axis direction are arranged in the X-axis direction when viewed in the entire liquid crystal layer 30.

  The pixel group 50 of the image display unit 120 is disposed to face the area AR <b> 1 between the two adjacent first electrodes 21. The convex lens-shaped refractive index distribution formed in the liquid crystal layer 30 faces the pixel group 50. In this example, the high refractive index portion (second portion 30 b) in the refractive index distribution of the liquid crystal layer 30 faces the second pixel PX <b> 2 disposed in the center of the pixel group 50.

  The refractive index distribution of the liquid crystal layer 30 during voltage application causes light (image) emitted from the pixel group 50 to travel toward the eyes of the observer. Thereby, an image formed by the plurality of first pixels PX1 included in the image display surface 120a becomes the first parallax image. An image formed by the plurality of second pixels PX2 is a second parallax image. An image formed by the plurality of third pixels PX3 is a third parallax image. The parallax image for the right eye is selectively incident on the right eye of the observer, and the parallax image for the left eye is selectively incident on the left eye of the observer. Thereby, 3D display becomes possible. That is, the liquid crystal optical element 110 enters the second state when a voltage is applied to the plurality of first electrodes 21 and the second electrodes 22.

  When the liquid crystal optical element 110 is in the first state, the light emitted from the pixel group 50 travels straight and enters the eyes of the observer. Thereby, 2D display becomes possible. In 2D display, a normal 2D image can be displayed with a resolution several times as large as that of 3D display (in this example, 3 times).

  The plurality of pixels PX can be provided with color filters each including RGB three primary colors. As a result, color display is possible. The color filter may further include white (colorless) and other color elements in addition to the RGB three primary colors.

  As described above, in the liquid crystal optical element 110 of the stereoscopic image display device 210, by changing the refractive index distribution of the liquid crystal layer 30 depending on whether or not a voltage is applied to the plurality of first electrodes 21 and second electrodes 22, Switch between 2D display and 3D display. In the liquid crystal optical element 110, a plurality of recesses 40 are provided on the facing surface 21 a of the first electrode 21.

  In the liquid crystal optical element 110, when switching from the first state to the second state, the direction of the director of the liquid crystal changes so as to approach the vertical alignment from the horizontal alignment. At this time, at least one of reverse tilt (reversal of the tilt direction of the liquid crystal) and twist (rotation of the director of the liquid crystal in the XY plane) occurs, and disclination occurs. This has been found to degrade the optical properties of the liquid crystal optical element.

  Since this disclination is established by balancing the alignment states at the boundaries of alignment domains having different tilt angles and twist angles, the disclination is in an unstable state. When some kind of trigger occurs, this disclination easily changes. For example, bending occurs along the extending direction of the electrode at a pitch several times the electrode width, and the width of the disclination region is several times or more that when bending does not occur. In a state in which the bending is remarkably generated, the influence of the disclination region on the deterioration of the optical characteristics of the liquid crystal optical element becomes very large. This is presumably because the width of the disclination region becomes several times larger due to the occurrence of bending.

  On the other hand, the present inventors have intensively studied the mechanism of occurrence of bending of disclination, and can control the bending of disclination by providing a plurality of recesses 40 in the plurality of first electrodes 21. I found. By providing a plurality of recesses 40 in the first electrode 21 or the periphery thereof, particularly in a region where the disclination is bent and reached, intentional bending of the disclination starting from the recesses 40 is generated. Can do. Then, by applying a predetermined device to the arrangement of the recesses 40, the width of the bending of the disclination can be kept small. As a result, it is possible to suppress an increase in the influence of disclination due to bending.

  In the stereoscopic image display apparatus 210, the occurrence of disclination and bending thereof causes a mixed viewing (crosstalk) of parallax images, and hinders the viewer's stereoscopic viewing. In the stereoscopic image display device 210, the occurrence of disclination can be suppressed and the visibility of the stereoscopic image display device 210 can be improved.

  In the stereoscopic image display device 210, the distance D1 between the two concave portions 40 adjacent to each other is set to be equal to or smaller than the width W1 of the first electrode 21 in the X-axis direction. As a result, the bending width of the disclination can be made equal to or smaller than the width W1 of the first electrode 21 in the X-axis direction, and the influence of the bending is suppressed, and the visibility of the stereoscopic image display device 210 is greatly improved. Can be made. In the stereoscopic image display device 210, the width W <b> 2 of the recess 40 is made larger than the distance D <b> 1 between the recess 40 and the adjacent recess 40. Thereby, the recessed part 40 can be effectively used as the starting point of the bending of the disclination, and the control performance of the bending can be improved. Further, in the stereoscopic image display device 210, the width W1 of the first electrode 21 in the X-axis direction is made larger than the depth D2 from the facing surface 21a of the recess 40. Thereby, the disclination bending | flexion control performance of the recessed part 40 can be improved more. This is because the width is more effective for controlling disclination than the depth of the recess 40.

FIG. 4A to FIG. 4E are schematic perspective views illustrating the configuration of a part of another stereoscopic image display device according to the first embodiment.
As shown in FIG. 4A, in the two recesses 40 adjacent to each other among the plurality of recesses 40 provided in the first electrode 21, the position of the recess 40 in the X-axis direction is the recess 40. It may differ from the position of the adjacent recessed part 40 in the X-axis direction. That is, the positions in the X-axis direction of the two concave portions 40 adjacent to each other may be relatively shifted. For example, the positions in the X-axis direction may be shifted every few pieces without being limited to the two adjacent recesses 40. By disposing them in this way, the controllability of the disclination bend can be further improved. That is, it is possible to control the bending of the disclination to a desired position by suppressing the phenomenon that the disclination position is deviated from the recess 40.

As illustrated in FIG. 4B, one linear recess 40 extending along the Y-axis direction may be provided in the first electrode 21. In FIG. 4B, a linear recess 40 is shown.
As shown in FIG. 4C, the width in the X-axis direction may be changed in the linear recess 40. FIG. 4C shows, for example, a recess 40 whose width in the X-axis direction gradually increases from the end connected to the wiring portion 41 toward the opposite end. The recess 40 may gradually narrow its width in the X-axis direction from the end connected to the wiring portion 41 toward the opposite end. Alternatively, the width in the vicinity of the center in the Y-axis direction may be maximized, and the width may be gradually reduced toward both ends. In FIG. 4C, the width in the X-axis direction is continuously changed from one end side to the other end side. The width of the recess 40 in the X-axis direction may be changed stepwise.

  As shown in FIG. 4D, the linear recess 40 may have a zigzag shape having a plurality of bent portions 40a whose angles change with respect to the Y-axis direction. In the recess 40 of FIG. 4D, a distance D3 in the Y-axis direction between two adjacent bent portions 40a is equal to or less than the width W1 of the first electrode 21 in the X-axis direction. Since the disclination tends to be naturally bent as described above, the position of the disclination bend can be best controlled by finely bending the linear recess 40 in advance. . In addition, the linear recessed part 40 may be curving in the waveform, for example.

  As shown in FIG. 4E, two linear recesses 40 may be provided on the first electrode 21 side by side in the X-axis direction. The number of linear recesses 40 is not limited to two, and may be three or more. That is, a plurality of linear recesses 40 may be provided on the first electrode 21 in the X-axis direction. The plurality of linear recesses 40 may be linear or zigzag. You may change the width | variety of each X-axis direction of the some linear recessed part 40. FIG.

  For example, the recess 40 may be formed by transferring a shape such as a hole provided in the first substrate 11 to the first electrode 21. Further, the recess 40 may be, for example, a hole, a groove, or a slit formed in the first electrode 21 itself.

(Second Embodiment)
FIG. 5 is a schematic cross-sectional view illustrating the configuration of a stereoscopic image display device according to the second embodiment.
As shown in FIG. 5, in the stereoscopic image display device 212 of this example, the first substrate unit 11 s of the liquid crystal optical element 112 further includes a plurality of electrode pairs 25. The plurality of electrode pairs 25 are provided between the plurality of first electrodes 21 on the first major surface 11a. The plurality of electrode pairs 25 are arranged in the second direction (X-axis direction). The plurality of first electrodes 21 are provided with recesses 40.

  Each of the plurality of electrode pairs 25 includes a third electrode 23 and a fourth electrode 24. The third electrode 23 extends in the Y-axis direction (first direction). The fourth electrode 24 extends in the Y-axis direction. In the liquid crystal optical element 112, the insulating layer 42 is provided between the first substrate 11 and the first electrode 21, and is provided between the third electrode 23 and the fourth electrode 24. A third electrode 23 extending in the first direction (Y-axis direction), a fourth electrode 24 extending in the first direction, and an insulating layer 42 are included. The insulating layer 42 is provided between the third electrode 23 and the fourth electrode 24. The insulating layer 42 may be continuous between the plurality of electrode pairs 25. In this example, the insulating layer 42 extends between the first electrode 21 and the first substrate 11.

  In FIG. 5, two of the plurality of first electrodes 21 are shown. The number of the plurality of first electrodes 21 is arbitrary.

  Attention is paid to the two closest first electrodes 21 among the plurality of first electrodes 21. There is a central axis 49 between the closest first electrodes 21. The central axis 49 passes through a midpoint that connects the centers of the two closest first electrodes 21 in the X-axis direction. The central axis 49 is parallel to the Y-axis direction.

  Attention is paid to one electrode 21p of the two closest first electrodes 21. The position 29 of the electrode 21p is the center position of the electrode 21 in the X-axis direction.

  In the first main surface 11a, a region between the central axis 49 and one electrode 21p of the two closest first electrodes 21 is defined as a first region R1. In the first main surface 11a, a region between the central axis 49 and the other electrode 21q of the two closest first electrodes 21 is defined as a second region R2. The direction from the central axis 49 toward the electrode 21p is the + X direction. The direction from the central axis 49 to the electrode 21q corresponds to the −X direction.

  In this example, one electrode pair 25 is provided in the first region R1. One electrode pair 25 is also provided in the second region R2. When projected onto the XY plane, the plurality of electrode pairs 25 are separated from each other. A region where no electrode is provided exists between the electrode pairs 25. In the embodiment, another electrode may be further provided between the electrode pairs 25.

  In one electrode pair 25, the third electrode 23 includes a first overlapping portion 23p that overlaps the fourth electrode 24 when projected onto a plane (XY plane) parallel to the first direction and the second direction. And a first non-overlapping portion 23q that does not overlap. In the one electrode pair 25, the fourth electrode 24 has a second overlapping portion 24p that overlaps the third electrode 23 when projected onto the XY plane, and a second non-overlapping portion 24q that does not overlap.

  In the liquid crystal optical element 112, the first overlapping portion 23p is disposed between the second overlapping portion 24p and the liquid crystal layer 30 in the electrode pair 25 included in the first region R1. The position of the third electrode 23 is shifted in the X-axis direction with respect to the position of the fourth electrode 24. Specifically, in one electrode pair 25, the distance between the second non-overlapping portion 24q and the central axis 49 is longer than the distance between the first non-overlapping portion 23q and the central axis 49. That is, in one electrode pair 25, the third electrode 23 is closer to the central axis 49 than the fourth electrode 24.

  The arrangement of the electrode pair 25 in the second region R2 is a substantially line-symmetric arrangement with the central axis 49 as the axis of symmetry. However, strict line symmetry is not necessary. For example, a minute asymmetry may be introduced based on the distribution of the alignment of the liquid crystal layer 30 (for example, a pretilt angle).

  When switching the liquid crystal optical element 112 from the first state to the second state, the driving unit 130 applies a first voltage between the first electrode 21 and the second electrode 22, for example, A third voltage is applied between the second electrode 22 and a fourth voltage is applied between the fourth electrode 24 and the second electrode 22. Here, even when the potential difference between the electrodes is set to zero, it is expressed that a voltage (voltage of 0 volt) is applied for convenience. The absolute value of the first voltage is larger than the absolute value of the third voltage. The absolute value of the first voltage is larger than the absolute value of the fourth voltage. The absolute value of the third voltage is larger than the absolute value of the fourth voltage. When these voltages are alternating current, the effective value of the first voltage is larger than the effective value of the third voltage. The effective value of the first voltage is larger than the effective value of the fourth voltage. The effective value of the third voltage is larger than the effective value of the fourth voltage. For example, the effective value of the first voltage is set larger than the effective value of the fourth voltage.

  When a voltage is applied as described above, in the portion of the liquid crystal layer 30 where the first electrode 21 and the second electrode 22 face each other, the liquid crystal molecules 35 that have been horizontally aligned become close to vertical alignment. . In the portion of the liquid crystal layer 30 near the center of the two adjacent first electrodes 21, the liquid crystal molecules 35 remain in horizontal alignment. In the portion of the liquid crystal layer 30 where the second electrode 22 and the third electrode 23 face each other, the liquid crystal molecules 35 that have been horizontally aligned are close to vertical alignment. In the portion of the liquid crystal layer 30 where the second electrode 22 and the second non-overlapping portion 24q of the fourth electrode 24 face each other, the liquid crystal molecules 35 remain in horizontal alignment.

  In the portion between the first electrode 21 and the fourth electrode 24, the refractive index gradually increases from the first electrode 21 toward the fourth electrode 24. In the vicinity of the boundary between the second non-overlapping portion 24q and the first overlapping portion 23p, the refractive index rapidly decreases from the fourth electrode 24 toward the third electrode 23. In the portion between the third electrode 23 and the central axis 49, the refractive index gradually increases from the third electrode 23 toward the central axis 49. Therefore, when a voltage is applied as described above, a Fresnel lens-like refractive index distribution having a refractive index step at a portion where the second electrode 22 and the electrode pair 25 face each other appears in the liquid crystal layer 30.

  In the liquid crystal optical element 112 that forms a Fresnel lens-like refractive index distribution in the liquid crystal layer 30, the thickness of the liquid crystal layer 30 can be reduced compared to the liquid crystal optical element 110. The response speed of the liquid crystal layer 30 in switching between the first state and the second state can be improved.

  In the liquid crystal optical element 112, the concave portion 40 is provided in the first electrode 21 to which a large absolute value (large effective value) is applied, so that the occurrence of bending of the disclination can be suppressed. Therefore, good optical characteristics can be obtained also in the liquid crystal optical element 112.

FIG. 6 is a schematic cross-sectional view illustrating the configuration of a part of another stereoscopic image display device according to the second embodiment.
As shown in FIG. 6, in the liquid crystal optical element 113, the concave portion 40 is provided in the third electrode 23. As described above, the recess 40 may be provided in the third electrode 23 to which a large absolute value (a large effective value) is applied. The third electrode 23 may be a part of the first electrode 21. That is, at least one of the first electrodes 21 includes a first non-overlapping portion that does not overlap with the first overlapping portion that overlaps the fourth electrode 24 when projected onto a plane parallel to the first direction and the second direction. The fourth electrode 24 has a second overlapping portion that overlaps the first electrode 21 and a second non-overlapping portion that does not overlap when projected onto the plane. For example, the third electrode 23 may be part of the first electrode 21, and the convex portion 46 may be provided only on the third electrode 23. For example, the third electrode 23 may be a part of the first electrode 21, and the recess 40 may be provided only in the third electrode 23.

(Third embodiment)
FIG. 7 is a schematic cross-sectional view illustrating the configuration of a stereoscopic image display device according to the third embodiment.
FIG. 8 is a schematic perspective view illustrating the configuration of a part of the stereoscopic image display apparatus according to the third embodiment.
FIG. 7 schematically shows a cross section taken along line B1-B2 of FIG. As shown in FIGS. 7 and 8, in the stereoscopic image display device 214 of this example, each of the plurality of first electrodes 21 of the liquid crystal optical element 114 has a convex portion 46 on the facing surface 21 a facing the second electrode 22. Have

  The plurality of first electrodes 21 each have a plurality of convex portions 46 arranged along the Y-axis direction. The plurality of convex portions 46 have substantially the same shape. The plurality of convex portions 46 have a rectangular parallelepiped shape, for example. For example, the plurality of convex portions 46 are arranged substantially in a straight line along the Y-axis direction. In addition, each of the plurality of convex portions 46 is periodically arranged, for example. Each of the plurality of convex portions 46 is arranged at substantially equal intervals, for example. For example, a material having an insulating property is used for the plurality of convex portions 46. For example, a resin material is used for the plurality of convex portions 46. For example, an inorganic material such as silicon oxide and an organic material such as an acrylic resin or a polyimide resin are used for the convex portion 46. The material used as the convex part 46 may have photosensitivity.

  A distance D4 between two adjacent protrusions 46 is equal to or less than the width W1 of the first electrode 21 in the X-axis direction. In the two adjacent convex portions 46, the width W3 of the convex portion 46 is larger than the distance D4 between the convex portion 46 and the adjacent convex portion 46. Further, the height D5 of the convex portion 46 from the facing surface 21a is smaller than the width W1 of the first electrode 21 in the X-axis direction. A height D5 of the convex portion 46 from the facing surface 21a is, for example, 1 μm (for example, 0.5 μm or more and 2 μm or less).

  In this way, even when the convex portion 46 is provided on the facing surface 21a, the occurrence of the bending of the disclination can be suppressed similarly to the concave portion 40. The protrusion 46 may be, for example, a protrusion formed on the first electrode 21 itself. Moreover, you may provide both the recessed part 40 and the convex part 46 in the opposing surface 21a. That is, the plurality of first electrodes 21 may be configured to have at least one of the concave portion 40 or the convex portion 46 on the facing surface 21 a facing the second electrode 22.

  For example, a coloring material (for example, a color resist containing at least one of a dye and a pigment) can be used for the plurality of convex portions 46. For example, the plurality of convex portions 46 are blue. For example, the transmittance in the wavelength region of 450 nm or more and 485 nm or less of the plurality of convex portions 46 is set higher than the transmittance in the wavelength region of less than 450 nm and more than 485. The 1st electrode 21 may have yellowishness. Moreover, the alignment film may have a yellowish color. If the plurality of convex portions 46 are made blue, the light transmitted through the first electrode 21 and the convex portions 46 can be made closer to white. Thereby, the color compensation of the stereoscopic image display device 214 can be performed.

  The plurality of convex portions 46 may be black as long as the transmittance can be reduced. For example, the transmittance of the plurality of convex portions 46 is made smaller than the transmittance of the first electrode 21. Thereby, the transmittance of the convex portion 46 can be lowered, and the influence of disclination can be reduced.

FIG. 9A to FIG. 9E are schematic perspective views illustrating the configuration of part of another stereoscopic image display device according to the third embodiment.
As shown in FIG. 9A, the positions in the X-axis direction of the plurality of convex portions 46 provided on the first electrode 21 may be different from each other, as with the concave portion 40. As shown in FIG. 9B, one linear protrusion 46 extending along the Y-axis direction may be provided on the first electrode 21. As shown in FIG. 9C, the width in the X-axis direction may be changed in the linear protrusion 46. Similar to the concave portion 40, the direction of change in the width in the X-axis direction is arbitrary in the convex portion 46. Further, the change in the width of the convex portion 46 in the X-axis direction may be continuous or stepwise.

  As shown in FIG. 9D, the linear convex portion 46 may have a zigzag shape having a plurality of bent portions 46a whose angles change with respect to the Y-axis direction.

  9D, a distance D6 in the Y-axis direction between two adjacent bent portions 46a is equal to or smaller than the width W1 of the first electrode 21 in the X-axis direction. Thereby, even if it is a convex-shaped shape, the bending of disclination can be controlled favorably. The linear convex part 46 may be curving in the waveform, for example.

  As shown in FIG. 9E, two linear protrusions 46 may be provided on the first electrode 21 side by side in the X-axis direction. The number of linear protrusions 46 is not limited to two, and may be three or more. That is, a plurality of linear protrusions 46 may be provided on the first electrode 21 in the X-axis direction. The plurality of linear protrusions 46 may be linear or zigzag. The width of each of the plurality of linear protrusions 46 in the X-axis direction may be changed.

FIG. 10 is a schematic cross-sectional view illustrating the configuration of another stereoscopic image display device according to the third embodiment.
As shown in FIG. 10, in the liquid crystal optical element 116 of the stereoscopic image display device 216 configured to form a refractive index distribution in the form of a Fresnel lens in the liquid crystal layer 30, a plurality of first electrodes 21 are provided on the first substrate 11. Provide. An insulating layer 42 that insulates the third electrode 23 and the fourth electrode 24 is provided on the first electrode 21. Then, the insulating layer 42 is patterned, and a part of the insulating layer 42 is left on the first electrode 21, thereby forming the convex portion 46 from the insulating layer 42. Thus, the convex portion 46 may be formed by processing the insulating layer 42 provided between the third electrode 23 and the fourth electrode 24. That is, the convex portion 46 includes substantially the same material as the insulating layer 42. Thereby, a process can be simplified.

FIG. 11 is a schematic cross-sectional view illustrating the configuration of a part of another stereoscopic image display device according to the third embodiment.
As shown in FIG. 11, in the liquid crystal optical element 117, the third electrode 23 is provided with a convex portion 46. As described above, the convex portion 46 may be provided on the third electrode 23 to which a large absolute value (a large effective value) is applied. The third electrode 23 may be a part of the first electrode 21. For example, a resin material or the like is used for the convex portion 46 of the third electrode 23. The convex portion 46 of the third electrode 23 may be formed separately from the insulating layer 42.

  According to the embodiment, a liquid crystal optical element having good optical characteristics and a stereoscopic image display device including the liquid crystal optical element are provided.

  In the present specification, “vertical” and “parallel” include not only strictly vertical and strictly parallel, but also include, for example, variations in the manufacturing process, and may be substantially vertical and substantially parallel. is good.

The embodiments of the present invention have been described above with reference to specific examples. However, embodiments of the present invention are not limited to these specific examples. For example, a first substrate unit, a second substrate unit, a liquid crystal layer, a first substrate, a first electrode, a second substrate, a second electrode, an electrode pair, a third electrode, which are included in a liquid crystal optical element and a stereoscopic image display device, With regard to the specific configuration of each element such as the fourth electrode, the insulating layer, and the image display unit, a person skilled in the art appropriately implements the present invention by appropriately selecting from a known range, and obtains the same effect. Is included in the scope of the present invention as long as possible.
Moreover, what combined any two or more elements of each specific example in the technically possible range is also included in the scope of the present invention as long as the gist of the present invention is included.

  In addition, all liquid crystal optical elements and stereoscopic image display devices that can be implemented by those skilled in the art based on the liquid crystal optical elements and stereoscopic image display devices described above as embodiments of the present invention are also included in the present invention. As long as the gist is included, it belongs to the scope of the present invention.

  In addition, in the category of the idea of the present invention, those skilled in the art can conceive of various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the present invention. .

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 11 ... 1st board | substrate, 11a ... 1st main surface, 11s ... 1st board | substrate part, 12 ... 2nd board | substrate, 12a ... 2nd main surface, 12s ... 2nd board | substrate part, 21 ... 1st electrode, 21a ... Opposite surface 21p, 21q ... electrode, 22 ... second electrode, 23 ... third electrode, 23p ... first overlapping portion, 23q ... first non-overlapping portion, 24th electrode, 24p ... second overlapping portion, 24q ... second Non-overlapping portion, 25 ... electrode pair, 30 ... liquid crystal layer, 30a ... first portion, 30b ... second portion, 31 ... first alignment film, 32 ... second alignment film, 35 ... liquid crystal molecule, 36 ... liquid crystal material, 40 ... concave portion, 40a ... bent portion, 41 ... wiring portion, 42 ... insulating layer, 42a ... hole, 46 ... convex portion, 49 ... central axis, 50 ... pixel group, 110, 112, 113, 114, 116, 117 ... Liquid crystal optical element, 120... Image display unit DESCRIPTION OF SYMBOLS 120a ... Image display surface, 130 ... Drive part, 210, 212, 214, 216 ... Stereoscopic image display apparatus, AR1 ... Area | region, D1, D3, D4, D6 ... Distance, D2 ... Depth, D5 ... Height, EL ... Electric field lines, PX, PX1, PX2, PX3 ... Pixel, R1, R2 ... Area, W1, W2, W3 ... Width

Claims (14)

A first substrate having a first major surface;
A plurality of first electrodes provided on the first main surface, extending along a first direction, and arranged in a second direction perpendicular to the first direction;
A first substrate part including:
A second substrate having a second main surface opposite to the first main surface;
A second electrode provided on the second main surface and facing each of the plurality of first electrodes;
A second substrate part including:
A liquid crystal layer provided between the first substrate unit and the second substrate unit;
With
At least one of the plurality of first electrodes is a liquid crystal optical element having a concave portion on a facing surface facing the second electrode. The first substrate unit includes an insulating layer provided between the first substrate and the first electrode and having a hole,
The liquid crystal optical element according to claim 1, wherein the concave portion is along the hole.   The liquid crystal optical element according to claim 1, wherein a plurality of the recesses are provided, and the plurality of recesses are arranged along the first direction.   The plurality of recesses include a first recess and a second recess adjacent to the first recess, and the distance between the first recess and the second recess is the first recess The liquid crystal optical element according to claim 3, wherein the liquid crystal optical element is equal to or smaller than a width of the electrode in the second direction.   The plurality of concave portions include a first concave portion and a second concave portion adjacent to the first concave portion, and the width of the first concave portion in the second direction and the second concave portion of the second concave portion. The liquid crystal optical element according to claim 3, wherein a width in the direction is larger than a distance between the first concave portion and the second concave portion.   The plurality of recesses include a first recess and a second recess next to the first recess, and the position of the first recess in the second direction center of the second direction is: The liquid crystal optical element according to claim 3, wherein the second concave portion is different from a position in the second direction at a center in the second direction.   The liquid crystal optical element according to claim 1, wherein the recess has a linear shape extending along the first direction.   The liquid crystal optical element according to claim 7, wherein a width of the concave portion along the second direction changes in the first direction.   The liquid crystal optical element according to claim 7, wherein the concave portion has a zigzag shape having a plurality of bent portions whose angles with respect to the first direction change.   The liquid crystal optical element according to claim 9, wherein a distance in the first direction between two bent portions adjacent to each other among the plurality of bent portions is equal to or less than a width of the first electrode in the second direction.   A plurality of the linear recesses extending along the first direction are provided, and the plurality of linear first electrodes extending along the first direction are arranged along the second direction. The liquid crystal optical element according to claim 7. The first substrate unit includes
A plurality of electrode pairs provided on each of the first main surfaces and arranged between the plurality of first electrodes and arranged in the second direction;
Each of the plurality of electrode pairs includes a third electrode extending in the first direction, a fourth electrode extending in the first direction, and an insulating layer provided between the third electrode and the fourth electrode. Have
The third electrode has a first non-overlapping portion that does not overlap with a first overlapping portion that overlaps the fourth electrode when projected onto a plane parallel to the first direction and the second direction,
The liquid crystal optical element according to claim 1, wherein the fourth electrode has a second overlapping portion that overlaps with the third electrode and a second non-overlapping portion that does not overlap when projected onto the plane. . The effective value of the first voltage applied between the plurality of first electrodes and the second electrode is larger than the effective value of the voltage applied between the third electrode and the second electrode,
The liquid crystal optical element according to claim 12, wherein an effective value of the first voltage is larger than an effective value of a voltage applied between the fourth electrode and the second electrode. A liquid crystal optical element according to any one of claims 1 to 13,
An image display unit laminated with the liquid crystal optical element and having an image display surface for displaying an image;
3D image display apparatus.

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